1. Technical Field
The present invention relates to potassium niobate deposited bodies and methods for manufacturing the same, piezoelectric thin film resonators, frequency filters, oscillators, electronic circuits, and electronic apparatuses.
2. Related Art
Accompanying the increase in communication speed in the data communications field, the development is directed toward achieving higher frequency in communication frequency. Piezoelectric thin film resonators (film bulk acoustic resonators: FBARs) are attracting attention as devices for achieving higher frequency. Piezoelectric thin film resonators are required to achieve higher electromechanical coupling coefficient for further miniaturization and higher efficiency.
It has been found that a single crystal substrate of potassium niobate (KNbO3) (a=0.5695 nm, b=0.3973 nm, and c=0.5721 nm; hereafter this index expression is followed as “orthorhombic crystal”) exhibited a high electromechanical coupling coefficient. For example, as described in Jpn. J. Appl. Phys. Vol. 37 (1998) 2929, it was confirmed by experiments that a 0° Y-cut X propagation KNbO3 single crystal substrate would exhibit a very large value of electromechanical coupling coefficient reaching as much as about 50%. However, it may be difficult to manufacture a piezoelectric thin film resonator by forming a potassium niobate thin film over a certain substrate having a large area.